1. Field of the Invention
The present invention relates generally to a sensing technique, and more particularly to an encoding device.
2. Description of the Related Art
A conventional sensing unit is used to detect the variation of the light, magnetic field or electrical field of a signal unit so as to measure the geometrical displacement of a mechanism. The obtained analog signals are converted into digital signals by an encoder, which is an inevitable component for achieving precise control in the field of precision mechanical technique. However, in order to provide precise displacement signals, as a precondition, the sensing unit and the signal unit of the encoder must be securely and precisely positioned in the relative positions so as to ensure that the signals are truly detected.
With a conventional encoder for optically detecting the rotational motion taken as an example, the signal unit is synchronously rotated with the rotary shaft. In addition, the signal transmitting end and the signal receiving end of the sensing unit are positioned on two sides of the signal unit in fixed positions opposite to each other so as to perform the measurement of the geometrical displacement. In such conventional technique, the signal unit and the sensing unit are disposed on suitable carrier members and previously located in the true relative positions, whereby by means of the carrier members, the signal unit can be indirectly synchronously rotated with the rotary shaft. Alternatively, the signal unit can be directly coupled on the rotary shaft and then the sensing unit is disposed to perform the rectification and alignment processes thereto.
In the conventional technique that the signal unit is directly coupled on the rotary shaft, when assembled, it is necessary to respectively perform the rectification and alignment processes between the sensing unit and the signal unit. To speak more specifically, when performing the rectification and alignment processes, it is necessary to externally connect the encoder to an oscilloscope for showing the waveform as the basis for the judgment of the rectification. Only when the waveform changes to meet a predetermined specification due to the adjustment of the position, the rectification and alignment processes are completed. Such procedure is quite complicated and will lead to inconvenience in manufacturing, assembling and processing processes. As a result, the manufacturing efficiency can be hardly enhanced.